1. Field of the Invention
The present invention relates to a developing device used for an image forming apparatus, a process cartridge detachable to an apparatus main body of the image forming apparatus, and the image forming apparatus for forming an image on a recording medium.
Image forming apparatuses described below exemplify image forming apparatuses for forming images on recording media. Therefore, an electro-photographic copying machine, an electro-photographic printer (such as a laser beam printer, a light-emitting diode (LED) printer), and a facsimile apparatus, which employ an electro-photographic image forming method are included as examples of the image forming apparatuses.
The developing device is a device for developing an electrostatic latent image formed on an image bearing member (electro-photographic photosensitive member), and a development unit (developing unit) disposed on a process cartridge is included. The process cartridge is configured in such a manner that an image bearing member and a processing unit such as a developing unit acting on the image bearing member are integrally formed into a cartridge, and this cartridge is detachably disposed on a main body (apparatus main body) of the image forming apparatus.
2. Description of the Related Art
Conventionally, in the image forming apparatus employing electro-photographic image forming processing, a photosensitive drum uniformly charged by a charging device is selectively irradiated with light such as laser light, LED light, or lamplight corresponding to image information. With this, an electrostatic latent image is formed on the photosensitive drum. Then, this electrostatic latent image is developed by the developing device (developing unit). Further, a developed image formed on the photosensitive drum is transferred to a recording medium, thereby forming an image on the recording medium.
The developing device includes a developing roller for supplying developer to the photosensitive drum, a developing chamber provided with a developer supply roller for supplying the developer to the developing roller, and a developer containing chamber for containing the developer that is to be supplied to the developing chamber.
There is provided a developing device in which a developer containing chamber is arranged on the lower side of the developing chamber. In such a case, developer has to be supplied upward in the anti-gravitational direction to the developing chamber from the developer containing chamber. Therefore, a developer conveyance member for drawing and conveying developer to supply the developer from the developer containing chamber to the developing chamber is disposed within the developer containing chamber.
Then, the developer supplied to the developing chamber is gradually used in the course of image forming processing. However, there may be a case where the developer stagnates on the bottom of the developing chamber at a rear side or a corner portion of the developing chamber. This stagnated developer may remain unused until the last moment.
Therefore, in order to stir and supply the developer in a stagnant portion to the developer supply roller, a configuration in which a stirring member is disposed within the developing chamber has been discussed (Japanese Patent Application Laid-Open No. 2011-39554). A configuration of a process cartridge including a stirring member discussed in Japanese Patent Application Laid-Open No. 2011-39554 is illustrated in FIG. 15.
In the configuration illustrated in FIG. 15, developer is conveyed by a conveyance member 236 from a developer containing chamber 231a to a developing chamber 231b where a developing roller 225 is disposed. A stirring member 260 is disposed in the developing chamber 231b, and by the stirring member 260 being driven, the developer conveyed to the developing chamber 231b is moved toward a developer supply roller 234 so as to be borne by the developer supply roller 234. Further, the developer is supplied from the developer supply roller 234 to the developing roller 225, thereby developing an electrostatic latent image formed on a photosensitive drum 201.
However, if such a stirring member discussed in Japanese Patent Application Laid-Open No. 2011-39554 is disposed, this may result in increase in number of components and assembling man-hours. Further, as for a position to which the stirring member cannot reach, the developer cannot be stirred, and thus there is a possibility that stagnation of the developer will not be suppressed.